Linux shell commands

A number of commands and trick that I regularly use in Linux to make my life easier.

!$

Typing !$ into a bash command will substitute the last argument from the previous command.

[gavin@pc]: date > test.txt
[gavin@pc]: cat !$
Mon Feb 22 12:02:53 WET 2010

!! will provide the whole of the previous command

[gavin@pc]: updatedb
updatedb: can not open a temporary file for `/var/lib/mlocate/mlocate.db'
[gavin@pc]: sudo !!

Adding bind Space:magic-space to ~/.bashrc will mean that pressing space after entering either of these commands will immediately convert (e.g. !$ will be replaced with test.txt).

!* provides all of the arguments from the previous line, e.g.

[gavin@pc]: touch a.txt b.txt c.txt
[gavin@pc]: chmod 777 !*

will create 3 files and set the permissions on each to 777.

Finally, using !somecommand will search backwards through the command history to match a command

[gavin@pc]: cat test.txt
[gavin@pc]: date > test.txt
[gavin@pc]: !ca
Mon Feb 22 12:02:53 WET 2010

You don’t have to enter the whole command, just enough to match the line you want.